Hello @Joe-and-Christine0,
Yes, as @Marit-Anne0 says you'll have to contact Airbnb support. You can't change your address yourself once a guest has completed a reservation.
Like usung google to search for things in general, you can use the search facility on these pages to find the ways to contact support.
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.